Monolithic Comparator and Sawtooth Generator of AlGaN/GaN MIS-HEMTs With Threshold Voltage Modulation for High-Temperature Applications
Ang Li, Miao Cui, Yi Shen, Ziqian Li, Wen Liu, Ivona Z. Mitrović, Huiqing Wen, Cezhou Zhao
Abstract
This article demonstrates the integrated comparators, hysteresis comparators, and sawtooth generators based on aluminum-gallium-nitride/gallium-nitride (AlGaN/GaN) metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs). The integrated circuits (ICs) exhibit thermal stability from 25 °C to 250 °C in both static and transient performances. The threshold voltage ( V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> ) in depletion (D)-mode MIS-HEMT is modulated from -8.9 to -2.4 V to optimize the performance of integrated comparator circuits. The comparator can realize a large and stable comparison range of 3-9 V and a high voltage swing of 9.1 V, while the hysteresis comparator exhibits a good noise-immunity ability and stable hysteresis output. The sawtooth generator with the hysteresis comparator features a high amplitude (6.1 V) sawtooth signal at 500 kHz to realize a compact structure applicable to the high-voltage mixed-signal circuits. These results show the feasibility of MIS-HEMT monolithic comparator circuits in conversion systems.